How to Fix Sonoff Device Fails Firmware Update in eWeLink
- Weak WiFi during the update
- Device dropping offline mid-update
- eWeLink servers busy
Problem Description
Your SONOFF device shows a firmware update available in eWeLink, but the update fails partway through — the progress bar stalls, the app shows an error, or the device reboots without completing the update. This happens most often with the BASICR4, MINIR4, and TH Elite models when WiFi signal is weak or the app loses its connection during the download. A failed firmware update can leave the device unresponsive if it was interrupted during the flash write.
Why This Happens in Real Homes
A SONOFF firmware update failing in eWeLink is almost always a connection issue — updates need a steady link to download and flash, so a weak WiFi signal, a device that drops offline mid-update, or busy eWeLink servers cause it to fail. A marginal connection that's fine for on/off can still be too shaky for an update.
Ensure the device has a strong, stable 2.4GHz connection (move it closer to the router temporarily if needed), reduce interference, and keep it online throughout. Retry after a few minutes in case the servers are busy. For Zigbee sensors, make sure the battery is fresh and the device has a solid link to the bridge before updating. Restart the device and retry if it stalls.
Symptoms
- Firmware update fails
- Update won't complete
- Stuck updating
- Repeated update failures
- Update available but won't install
- Times out updating
- Update error in eWeLink
- Fails partway
Recognize these? Here's what usually causes it.
Common Causes
- Weak WiFi during the update
- Device dropping offline mid-update
- eWeLink servers busy
- Slow connection timing out
- Device too far from the router
- Interference on 2.4GHz
- Low battery (Zigbee devices)
- Router blocking the update
Most fixes happen in the first 3 steps.
Do not interrupt power while firmware is writing.
Tools & Requirements
Step-by-Step Solution
Check WiFi signal strength before updating
Firmware updates download directly to the SONOFF device over WiFi. If the signal is weak (below -70 dBm), the download stalls or corrupts mid-transfer. Check signal in eWeLink: tap the device > ··· > Device Info. If the signal is weak, temporarily move a WiFi access point closer to the device before attempting the update. Do not start a firmware update over a marginal connection — a failed mid-update can leave the device in a boot loop.
Keep the device powered throughout the update
SONOFF devices (BASICR4, MINIR4, POW Elite, S40, etc.) must stay powered during the entire firmware update — typically 1-4 minutes. If the device loses power mid-flash, it can brick. Do not flip the breaker or wall switch during the update. The eWeLink app shows a progress bar. Wait for the 'Update successful' message and the device to come back online before touching anything. If the device is on a circuit with other heavy loads (AC units, space heaters), avoid running those during the update to prevent voltage drops.
Force close eWeLink and retry
If the update fails with a generic error or times out: force close the eWeLink app completely (swipe it away from the app switcher, don't just minimize). Reopen eWeLink, go to the device, and tap ··· > Firmware Update again. Sometimes the app loses the download session and needs a fresh start. Make sure your phone stays on the same WiFi network as the SONOFF device during the entire update — switching between WiFi and cellular mid-update causes failures.
Factory reset and re-pair if the update keeps failing
If the device repeatedly fails to update: it may have a corrupted config preventing the update process from starting. Factory reset: hold the device button for 5+ seconds until the LED blinks rapidly. Then re-pair it in eWeLink (Add Device > Quick Pairing). After re-pairing, try the firmware update again. The fresh pairing clears any corrupted network or config state that was blocking the update process.
Try updating through a DIY firmware tool
For advanced users: some SONOFF devices support OTA updates through the SONOFF DIY mode (available on BASICR3, BASICR4, MINIR3/R4, and other R-series devices). Long-press the small button on the circuit board (accessible through the case opening or by removing the cover) for 5 seconds to enter pairing mode, then press 3 quick taps to enter DIY mode — the LED blinks in a distinct pattern. Connect to the device's own AP (ITEAD-XXXXXXXXXX) and access the REST API at 8081. This bypasses eWeLink entirely. Only use this if you are comfortable with HTTP API calls — incorrect firmware files can brick the device.
Quick Solutions
Still having issues? This is usually the deeper cause below.
If the device became unresponsive after a firmware update, a factory reset usually clears the corrupted state — the update itself is rarely the root cause.
Update devices in small batches to reduce risk.
Firmware updates that wipe settings are more common than brands admit — many devices silently reset to factory defaults on an OTA push with no warning.
- Weak WiFi during the update
- Device dropping offline mid-update
- eWeLink servers busy
- Slow connection timing out
- Device too far from the router
Before you go — try one of these (they fix most cases).
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Official Manufacturer Manual
SONOFF provides official product documentation through their online manual rather than downloadable PDF. Access setup guides, troubleshooting steps, and product specifications for your Sonoff Firmware Updates.
Source: sonoff.tech
Need More Help? SONOFF Support
Note: The contact information below connects you directly to SONOFF's official customer support team, not Trunetto. They can help with warranty claims, device replacements, and advanced technical issues.
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